European Union leaders, meeting at a two-day summit in Seville, Spain, have agreed to step up efforts to fight a growing tide of illegal immigrants to the prosperous 15-nation bloc. But they are backing away from a controversial proposal to punish nations that do not prevent their citizens from seeking to enter Western Europe illegally.

The proposal to threaten financial and trade sanctions against non-EU countries that fail to control the exodus of their nationals to Western Europe was put forward by Spain, with the backing of Britain and Italy. It is part of a package of measures that European leaders are pushing to combat illegal immigration into the bloc.

EU member states agree on the need to tighten border controls, harmonize their individual asylum and immigration policies and step up expulsions of non-EU citizens whose applications for asylum have been rejected by European governments.

The sudden pressure to deal with illegal immigration comes in the wake of electoral successes by populist far-right parties in several EU countries. Mainstream politicians have said they need to assure EU citizens that they are prepared to get tough on illegal immigration in a bid to neutralize the extremists.

Meeting Friday with reporters, Spanish foreign minister Josep Pique indicated that his country has toned down its initial idea of putting the burden of illegal immigration on their countries of origin.

"Europe needs legal immigrants," he said. "It needs to guarantee their rights and integrate them into society. But the only way to do that, he adds, is to clamp down on illegal immigrants," he said.

Mr. Pique said the EU will work with countries whose citizens try to get into Western Europe without the proper documentation. He said it will offer financial and other help to those countries. He said any measures taken against a third country that fails to cooperate with the EU drive to stamp out illegal immigration must meet with the unanimous approval of all 15 EU members.

France, Sweden and Belgium have been adamant in maintaining that cutting off aid or trade preferences to countries that are unable to prevent their citizens from going to the EU can only make matters worse.

That view was echoed Friday by Pat Cox, president of the European Parliament.

"We incline to the view that, if one operated a sanctions policy, because, clearly, in first principles, you can argue for it, then it runs the serious risk of being counterproductive and of, indeed, creating the possibility of further migration when the very hypothesis was to lessen that prospect," he said.

With the immigration debate out of the way for the time being, the leaders moved on to discuss institutional reforms designed to make the bloc more efficient once it admits 10 new members from Eastern and Southern Europe by the year 2004. But the whole process of enlargement could be thrown into doubt in the months ahead by a dispute over how much money should be given to farmers in the candidate countries.

The summit is meeting amid tight security. Two bombs, one of which injured six people, went off in the beachside resorts of Fuengirola and Marbella, southeast of Seville. Police said they were probably set off by the Basque separatist group ETA.